Lithium hydroxide, monohydrate → 5-[(tert-butoxy)carbonyl]-1H,4H,5H,6H,7H-pyrazolo[4,3-c]pyridine-3-carboxylic acid

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Reaction Steps

A solution of 1,4,6,7-tetrahydro-pyrazolo[4,3-c]pyridine-3,5-dicarboxylic acid 5-tert-butyl ester 3-ethyl ester [5.105 g, Reference Example 18(d)] and lithium hydroxide monohydrate (0.870 g) in methanol (30 ml) and water (10 ml) was stirred at 55° C. for 2.5 hours. The mixture was acidified with saturated aqueous potassium hydrogen sulfate solution and extracted three times with ethyl acetate. The organic extracts were combined, dried over magnesium sulfate and concentrated in vacuo to yield 1,4,6,7-tetrahydro-pyrazolo[4,3-c]pyridine-3,5-dicarboxylic acid 5-tert-butyl ester (4.442 g) as a pale yellow solid. MS: 268 (M+H)+. HPLC (METHOD G): RT=2.86 minutes.

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